Input: ili210x - add ili2120 support

This adds support for the Ilitek ili2120 touchscreen found in the
Fairphone 2 smartphone.

Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Link: https://lore.kernel.org/r/20200209151904.661210-1-luca@z3ntu.xyz


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>